ETMY was TRIPPED at 11:42:15 JST today (fig1).
The reason seems that strange behaviour of H1 photosensors, so I disabled watchdog for IMH1 photosensor.
Since this photosensor is used for NBDAMP_{L1,T1}, it should be consider how to damp these two modes.
I am not so sure the exact reason why the sensor became strange but we have had many experiences that sensors became strange during cooling.
So, it would be due to thermal stress on the cables inside the cryostat due to cooling.
To recover the suspensions, I modified ETMY_IM_OSEM2EUL matrix from the one in fig1 to the one in fig2.
In this modification, Y2L, Y2T, and L2Y coupling cannot be canceled, so these coupling would be increased a lot but it would be fine because these signals are only using for NBDAMP and Y resonances are far from the L/T resonances.
After the modification, I requested the LOCK_ACQUISITION state and confirmed ETMY can reach LOCK_ACQUISITION state without problems.
Since I haven't checked the spectra of the signals, it would be better to measure it and compare with the one before IMH1 photosensor trouble.
Note:
Since DGS maintainance is ongoing, I also don't chack IFO can be locked with this new configuration.
So, it should be also checked soon.
I confirmed that the new matrix (and damping) works well at this moment and IFO can reach OBSERVATION state without any problems.
